Nuclear radiation detection

ABSTRACT

A nuclear radiation detector is disclosed. The detector includes a housing including therein: a scintillator; and a multi-pixel optical sensor positioned, relative to the scintillator, to receive photons emitted by the scintillator in response to interactions with nuclear radiation. The housing isolates the scintillator and the multi-pixel optical sensor from external light. The detector includes one or more processors operably connectable to the multi-pixel optical sensor; and one or more data stores coupled to the processors having instructions stored thereon which cause the processors to perform operations. The operations include: responsive to the multi-pixel optical sensor detecting photons emitted by the scintillator, receiving, from the multi-pixel optical sensor, data signals indicating 1) spatial locations of individual pixels that detected the photons and 2) temporal data indicating when the detections occurred; and generating, from the data signals, a spatially and temporally resolved image of radiation incident on the scintillator.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Application No. 62/942,313,filed Dec. 2, 2019, which is incorporated by reference in its entirety.

BACKGROUND

Radiation detectors are used to detect nuclear radiation includingneutron radiation and gamma radiation. One exemplary type of radiationdetector employs a scintillator. The scintillator includes a materialthat emits photons in response to interactions with incident nuclearradiation. The emitted photons are proportional to the amount ofradiation present in a given area, but generally do not indicatedirectionality of the sensed radiation.

SUMMARY

In general, the disclosure relates to detecting nuclear radiation. Morespecifically, the disclosure relates to a system for generating imagesof nuclear flux using a combination of scintillators and multi-pixeloptical sensors.

Nuclear radiation measurement and imaging can be used in fields such asplasma creation, materials science, medical isotope generation, spacepropulsion, fusion and fission energy. In nuclear radiation measurement,it may be desirable to resolve spatial, time, energy, and wavelengthcharacteristics of nuclear radiation.

Nuclear radiation, e.g., neutron and gamma radiation, can interact withscintillator material to produce photons which are measurable withoptical detectors. An example optical detector is a multi-pixel opticalsensor, such as a dynamic vision sensor (DVS), or event camera. Pixelsof a DVS can trigger based on changes in brightness. A DVS can resolvechanges in pixel brightness accurately to under one millisecond. One ormore DVSs optically coupled to one or more scintillators can provide aspatially and time resolved image of neutron flux. Several arrangementsof scintillators and DVSs can be implemented for improved spatial, time,and spectral characterization of nuclear flux.

In general, innovative aspects of the subject matter described in thisspecification can be embodied in a nuclear radiation detector. Thenuclear radiation detector includes a housing including therein: ascintillator; and a multi-pixel optical sensor positioned, relative tothe scintillator, to receive photons emitted by the scintillator inresponse to interactions with nuclear radiation. The housing isolatesthe scintillator and the multi-pixel optical sensor from external light.The detector includes one or more processors operably connectable to themulti-pixel optical sensor; and one or more data stores coupled to theone or more processors having instructions stored thereon which, whenexecuted by the one or more processors, causes the one or moreprocessors to perform operations. The operations include: responsive tothe multi-pixel optical sensor detecting photons emitted by thescintillator, receiving, from the multi-pixel optical sensor, datasignals indicating 1) spatial locations of individual pixels thatdetected the photons and 2) temporal data indicating when the detectionsoccurred; and generating, from the data signals, a spatially andtemporally resolved image of radiation incident on the scintillator.

These and other embodiments may each optionally include one or more ofthe following features. In some implementations, the multi-pixel opticalsensor is a dynamic vision sensor.

In some implementations, a time resolution of the image is less than onemillisecond.

In some implementations, the scintillator is positioned between a firstreflector and a second reflector, each of the first reflector and thesecond reflector including a reflective surface that faces opposite sidesurfaces of the scintillator. The multi-pixel optical sensor ispositioned adjacent an edge of the scintillator that is not bounded byeither the first reflector or the second reflector.

In some implementations, the scintillator is a large-area scintillator,the detector further including a lens positioned to focus photonsemitted by the scintillator in response to interactions with nuclearradiation onto the multi-pixel optical sensor.

In some implementations, the lens is positioned between the large-areascintillator and the multi-pixel optical sensor, and the large-areascintillator, the lens, and the multi-pixel optical sensor aresubstantially aligned.

In some implementations, the operations further include: determining,from the spatially and temporally resolved image of radiation incidenton the scintillator, one or more nuclear radiation flux characteristics.

In some implementations, the one or more nuclear radiation fluxcharacteristics include at least one of a velocity, a direction oftravel, a wavelength, and an energy of the radiation incident on thescintillator.

In some implementations, the multi-pixel optical sensor is positionedwith light-sensitive regions of the pixels facing the scintillator.

In some implementations, the housing further includes therein: a secondscintillator spaced from the scintillator; and a second multi-pixeloptical sensor positioned, relative to the second scintillator, toreceive photons emitted by the second scintillator in response tointeractions with nuclear radiation. The housing isolates the secondscintillator and the second multi-pixel optical sensor from externallight. The operations further include: responsive to the secondmulti-pixel optical sensor detecting photons emitted by the secondscintillator, receiving, from the second multi-pixel optical sensor,data signals indicating 1) spatial locations of individual pixels thatdetected the photons and 2) temporal data indicating when the detectionsoccurred; generating, from the data signals, a second spatially andtemporally resolved image of radiation incident on the secondscintillator; and determining, from the spatially and temporallyresolved image of radiation incident on the scintillator, and the secondspatially and temporally resolved image of radiation incident on thesecond scintillator, a nuclear radiation velocity and direction betweenthe scintillator and the second scintillator.

In some implementations, one or more of the scintillator and the secondscintillator emits photons in response to interactions with neutrons.

In some implementations, one or more of the scintillator and the secondscintillator emits photons in response to interactions with gamma rays.

In some implementations, the scintillator, the multi-pixel opticalsensor, the second scintillator, and the second multi-pixel opticalsensor are substantially aligned.

In another general aspect, a nuclear radiation detection systemincludes: a housing including therein: a scintillator; and a multi-pixeloptical sensor positioned, relative to the scintillator, to receivephotons emitted by the scintillator in response to interactions withnuclear radiation. The housing isolates the scintillator and themulti-pixel optical sensor from external light. The system includes oneor more processors operably connectable to the multi-pixel opticalsensor; a display operably coupled to the one or more processors; andone or more data stores coupled to the one or more processors havinginstructions stored thereon which, when executed by the one or moreprocessors, causes the one or more processors to perform operations. Theoperations include: responsive to the multi-pixel optical sensordetecting photons emitted by the scintillator, receiving, from themulti-pixel optical sensor, data signals indicating 1) spatial locationsof individual pixels that detected the photons and 2) temporal dataindicating when the detections occurred; generating, from the datasignals, a spatially and temporally resolved image of radiation incidenton the scintillator; and providing, for presentation on the display, thespatially and temporally resolved image of the radiation incident on thescintillator.

These and other embodiments may each optionally include one or more ofthe following features. In some implementations, the multi-pixel opticalsensor is a dynamic vision sensor.

In some implementations, a time resolution of the image is less than onemillisecond.

In some implementations, the scintillator is positioned between a firstreflector and a second reflector, each of the first reflector and thesecond reflector including a reflective surface that faces opposite sidesurfaces of the scintillator. The multi-pixel optical sensor ispositioned adjacent an edge of the scintillator that is not bounded byeither the first reflector or the second reflector.

In some implementations, the scintillator is a large-area scintillator,the detector further including a lens positioned to focus photonsemitted by the scintillator in response to interactions with nuclearradiation onto the multi-pixel optical sensor.

In some implementations, the lens is positioned between the large-areascintillator and the multi-pixel optical sensor, and the large-areascintillator, the lens, and the multi-pixel optical sensor aresubstantially aligned.

In another general aspect, a method for nuclear radiation detectionincludes: receiving, from a multi-pixel optical sensor that ispositioned, relative to a scintillator, to receive photons emitted bythe scintillator in response to interactions with nuclear radiation,data signals indicating 1) spatial locations of individual pixels thatdetected the photons and 2) temporal data indicating when the detectionsoccurred; generating, from the data signals, a spatially and temporallyresolved image of radiation incident on the scintillator; and providing,for presentation on a display, the spatially and temporally resolvedimage of the radiation incident on the scintillator.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an exemplary nuclear radiation detector with amulti-pixel optical sensor according to implementations of the presentdisclosure.

FIG. 2 is a diagram of an exemplary nuclear radiation detector with morethan one multi-pixel optical sensor according to implementations of thepresent disclosure.

FIG. 3 is a diagram of an exemplary nuclear radiation detector withreflective surfaces around a scintillator according to implementationsof the present disclosure.

FIG. 4 is a diagram of an exemplary nuclear radiation detector withreflective surfaces around each of a plurality of scintillatorsaccording to implementations of the present disclosure.

FIG. 5 is a diagram of an exemplary nuclear radiation detector with alarge-area scintillator according to implementations of the presentdisclosure.

FIG. 6 depicts a schematic diagram of a computer system that may beapplied to any of the computer-implemented methods and other techniquesdescribed herein.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 is a diagram of an exemplary nuclear radiation detector 100 witha multi-pixel optical sensor according to implementations of the presentdisclosure. The detector 100 includes a housing 110, a scintillator 120,and a multi-pixel optical sensor 130. The detector 100 can also includea power source 116, a processor 112, a display 118, and a data storage114. The power source 116 can be, but is not limited to, a battery (orbattery bank), a solar power source, or an external power source. Theprocessor 112 can be configured to execute software instructions storedin the data storage 114. The processor 112 can receive output signalsfrom the multi-pixel optical sensor 130 and process the signals todetermine characteristics of incident nuclear radiation.

The housing 110 encloses the scintillator 120 and the multi-pixeloptical sensor 130. The housing 110 can isolate the scintillator 120 andthe multi-pixel optical sensor 130 from external light. For example, thehousing can isolate the scintillator 120 and optical sensor 130 fromexternal light to prevent false radiation detection signals.

The scintillator 120 includes a luminescent material. When thescintillator 120 interacts with nuclear radiation, the scintillator 120absorbs energy from the nuclear radiation and emits the absorbed energyin the form of light, e.g., photons. The scintillator 120 can includeany type of luminescent material, e.g., organic or inorganic crystals,liquids, or glasses. The scintillator 120 emits photons in response tointeractions with nuclear radiation such as neutrons, gamma rays, orboth neutrons and gamma rays.

The multi-pixel optical sensor 130 is positioned, relative to thescintillator 120, to receive photons emitted by the scintillator 120 inresponse to interactions with nuclear radiation. For example, themulti-pixel optical sensor 130 can be positioned in relative alignmentwith the scintillator 120. In some examples, the multi-pixel opticalsensor 130 can be positioned such that the scintillator 120 is betweenthe multi-pixel optical sensor 130 and a radiation source. In someexamples, the multi-pixel optical sensor 130 can be positioned withlight sensitive regions of pixels directed towards (e.g., facing) thescintillator 120. In some examples, the multi-pixel optical sensor 130is positioned within a minimum and maximum distance to the scintillator120, e.g., from directly in contact with the scintillator 120 to onehundred centimeters from the scintillator 120.

The multi-pixel optical sensor 130 can be a camera that producesmulti-pixel images from incoming light. The multi-pixel optical sensor130 can be implemented as, for example, a dynamic vision sensor (DVS), acharge coupled device (CCD) array, or other appropriate optical sensingdevice. For instance, each pixel of a DVS can operate independently.Each pixel is activated in response to changes in detected brightness.Since the pixels of a DVS respond to changes in brightness, but remaininactive otherwise, a DVS can produce accurate representations of pixelbrightness changes at a high temporal resolution. For example, a DVS maybe able to detect pixel brightness changes with a temporal resolution ofless than one millisecond.

In operation, a nuclear radiation source 102 emits nuclear radiation,e.g., a neutron 104. The neutron 104 travels with a directionrepresented by arrow 106. The neutron 104 enters the housing 110 andimpacts the scintillator 120. The scintillator 120 absorbs energy fromthe neutron 104 and emits the energy as a photon 124. As a result ofinteracting with the scintillator 120, the neutron 104 may slow anddeflect. The neutron 104 can continue to travel through the scintillator120 and the housing 110 at a direction represented by arrow 108.

The multi-pixel optical sensor 130 receives the photon 124 at one ormore pixels. The multi-pixel optical sensor 130 can transmit photon datasignals 122 to the processor 112. The photon data signals 122 canindicate spatial locations of individual pixels that detected the photon124. The photon data signals 122 can also indicate temporal dataindicating the relative timing between different photon detections.

The processor 112 can generate, from the photon data signals 122, aspatially and temporally resolved image of radiation incident on thescintillator 120. The processor 112 can control operation of the display118 to present the image.

Though the example of FIG. 1 is described with reference to neutronradiation, the detector 100 can also be configured to detect gammaradiation or a combination of neutron and gamma radiation.

FIGS. 2-5 illustrate additional configurations of scintillators andmulti-pixel optical sensors according to implementations of the presentdisclosure. Detector operation in FIGS. 2-5, including operations of thehousing, power source, processor, data storage, and display, are similarto operations of the detector 100 described with reference to FIG. 1.

FIG. 2 is a diagram of an exemplary nuclear radiation detector 200 withmore than one multi-pixel optical sensor according to implementations ofthe present disclosure. The detector 200 includes a housing 210, aneutron scintillator 220, and a first multi-pixel optical sensor 230.The detector 200 also includes a neutron/gamma scintillator 240 and asecond multi-pixel optical sensor 250. The neutron scintillator 220includes materials that interacts highly with neutrons, but does notinteract highly with gamma rays. For example, the neutron scintillator220 may have a higher nuclear cross section for neutrons than forgammas, where the nuclear cross section characterizes the probabilitythat a nuclear reaction will occur. The neutron/gamma scintillator 240includes materials that interact highly with both neutrons and gammarays, e.g., the neutron/gamma scintillator 240 has a similar nuclearcross section for both neutrons and gamma rays. Similar to the detector100, though not shown in FIG. 2, the detector 200 operably connects to apower source, a processor, a display, and a data storage.

The first multi-pixel optical sensor 230 is positioned, relative to theneutron scintillator 220, to receive photons emitted by the neutronscintillator 220 in response to interactions with nuclear radiation. Forexample, the first multi-pixel optical sensor 230 can be positioned inrelative alignment with the neutron scintillator 220. In some examples,the first multi-pixel optical sensor 230 can be positioned such that theneutron scintillator 220 is between the first multi-pixel optical sensor230 and a radiation source. In some examples, the first multi-pixeloptical sensor 230 can be positioned with light sensitive regions ofpixels directed towards (e.g., facing) the neutron scintillator 220.

The second multi-pixel optical sensor 250 is positioned, relative to theneutron/gamma scintillator 240, to receive photons emitted by theneutron/gamma scintillator 240 in response to interactions with nuclearradiation. For example, the second multi-pixel optical sensor 250 can bepositioned in relative alignment with the neutron/gamma scintillator240. In some examples, the second multi-pixel optical sensor 250 can bepositioned such that the neutron/gamma scintillator 240 is between thesecond multi-pixel optical sensor 250 and a radiation source. In someexamples, the second multi-pixel optical sensor 250 can be positionedwith light sensitive regions of pixels facing the neutron/gammascintillator 240.

In some examples, the neutron scintillator 220, first multi-pixeloptical sensor 230, neutron/gamma scintillator 240, and secondmulti-pixel optical sensor 250 are all positioned in relative alignment.For example, the scintillators 220, 240 and optical sensors 230, 250 canbe aligned such that nuclear radiation from the source 202 will interactwith both scintillators 220 and 240 in sequence. That is, nuclearradiation emitted from the source may interact with both the neutronscintillator 220 and the neutron/gamma scintillator 240, causing photonsto be detected at both the first multi-pixel optical sensor 230 and thesecond multi-pixel optical sensor 250 in sequence. Moreover, the aboveconfiguration creates a time delay between the sequential photondetections which can be processed to determine characteristics of theradiation (e.g., velocity, energy, and/or direction of travel).

As noted above, in some examples, the neutron scintillator 220 onlyinteracts highly with neutron radiation, while the neutron/gammascintillator 240 interacts highly with both neutron and gamma radiation.In such examples, the relative alignment between the scintillators 220,240 and optical sensors 230, 250 provides for output photon data signals222, 232 that can be interpreted to distinguish between different typesof radiation. For example, gamma radiation will interact highly withonly the neutron/gamma scintillator 240, causing photons to be detectedby only the second multi-pixel optical sensor 250, while neutronradiation will interact highly with either or both of the scintillators220 and 240, causing photon detections at either or both of the opticalsensors 230 and 250. Accordingly, neutron radiation can be positivelydistinguished when a photon detection occurs at the first multi-pixeloptical sensor 230 and gamma radiation is likely when a detection occursonly at the second multi-pixel optical sensor 250.

In some examples, the detector 200 can include more than onescintillator that interacts highly with both neutrons and gammas. Thedetector can differentiate between neutrons and gammas based onanalyzing characteristics of the neutron and gamma interaction with thescintillators. For example, the processor can analyze a decay profile ofthe fluorescence of a photon released by a scintillator to determinewhether the photon was produced through neutron interaction or gammainteraction.

The processor can also analyze the time between nuclear interaction witha first scintillator and nuclear interaction with a second scintillatorto determine time-of-flight of the nuclear radiation. Gamma rays travelat the speed of light, while neutrons can travel at a wide range ofspeeds that are slower than the speed of light. Thus, based on the timeof flight of the nuclear radiation between the first scintillator andthe second scintillator, the processor can determine whether theinteractions were produced through neutron interaction or gammainteraction.

In operation, a nuclear radiation source 202 emits nuclear radiation,e.g., a neutron 204 and a gamma ray 214. The neutron 204 travels with adirection represented by arrow 206. The neutron 204 enters the housing210 and impacts the neutron scintillator 220. The neutron scintillator220 absorbs energy from the neutron 204 and emits the energy as a photon224. As a result of interacting with the neutron scintillator 220, theneutron 204 may slow and deflect. The neutron 204 can continue to travelthrough the neutron scintillator 220 and the housing 210 at a directionrepresented by arrow 212.

The first multi-pixel optical sensor 230 receives the photon 224 at oneor more pixels. The multi-pixel optical sensor 230 can transmit photondata signals 222 to the processor. The photon data signals 222 canindicate spatial locations of individual pixels that detected the photon224. The photon data signals 222 can also include temporal dataindicating the relative timing between different photon detections.

The gamma ray 214 travels with a direction represented by arrow 216. Thegamma ray 214 enters the housing 210 and passes through the neutronscintillator 220. The gamma ray 214 impacts the neutron/gammascintillator 240. The neutron/gamma scintillator 240 absorbs energy fromthe gamma ray 214 and emits the energy as a photon 236.

The neutron 204 travels with a direction represented by arrow 212. Theneutron 204 impacts the neutron/gamma scintillator 240. Theneutron/gamma scintillator 240 absorbs energy from the neutron 204 andemits the energy as a photon 234.

The second multi-pixel optical sensor 250 receives each of the photons234, 236 at one or more pixels. The multi-pixel optical sensor 250 cantransmit photon data signals 232 to the processor. The photon datasignals 232 can indicate spatial locations of individual pixels thatdetected the photons 234, 236. The photon data signals 232 can alsoinclude temporal data indicating the relative timing between differentphoton detections.

The photon data signals 222, 232 can include additional data related tothe incident photons 224, 234, 236. For example, the photon data signals222, 232 can include data related to energy levels and wavelengths ofthe incident photons 224, 234, 236.

The processor can generate, from the photon data signals 222, 232,spatially and temporally resolved images of radiation incident on thescintillators 220, 240. The processor can control operation of thedisplay to present the image.

The processor can analyze the photon data signals 222, 232 and theimages of incident radiation to determine additional characteristics ofnuclear flux. For example, the processor can determine from the datasignals 222, 232 the time of travel of the neutron 204 between theneutron scintillator 220 and the neutron/gamma scintillator 240. Theprocessor can also compare the pixels activated in the first multi-pixeloptical sensor 230 and the second multi-pixel optical sensor 250 todetermine a direction of travel of the neutron 204 between the neutronscintillator 220 and the neutron/gamma scintillator 240. Thus, from thephoton data signals 222, 232, and the resulting images of radiationincident on the scintillators, the processor can determine nuclear fluxcharacteristics, e.g., velocity and direction, of the incident nuclearradiation.

Since the nuclear detector 200 includes both the neutron scintillator220 and the neutron/gamma scintillator 240, the processor can determinegamma flux characteristics independently of neutron fluxcharacteristics. By including multiple multi-pixel optical sensors, thenuclear detector 200 can produce time and space resolved images ofneutron and gamma flux, and can discern between neutron radiation andgamma radiation.

The processor can analyze the photon data signals 222, 232 to correctfor multiple nuclear radiation interactions and to performreconstruction of the nuclear radiation spatial, temporal, energy, andwavelength characteristics. For example, computationally intensive MonteCarlo simulations of neutron 204 and gamma ray 214 travel along the pathfrom the neutron source 202 to the detector 200 can be performed beforean experiment. Statistics of simulated detector signals based on theMonte Carlo simulations can be predicted before the experiment. Astatistical fitting or classifying algorithm such as linear regression,or a neural network with parameters tuned using the Monte Carlosimulation results can be implemented in real-time during the experimentfor feedback, or can be implemented for post-processing data analysisafter the experiment.

Though FIG. 2 illustrates a detector 200 with the neutron scintillator220 and the neutron/gamma scintillator 240, other scintillatorcombinations are possible. For example, a detector can include anynumber or combination of neutron scintillators, gamma scintillators, andneutron/gamma scintillators. The arrangement of neutron scintillators,gamma scintillators, and neutron/gamma scintillators can be in any orderwith respect to the direction of incident nuclear radiation. Eachmulti-pixel optical sensor can be positioned to receive photons from anycombination of one or more scintillators.

FIG. 3 is a diagram of an exemplary nuclear radiation detector 300 withreflective surfaces around a scintillator according to implementationsof the present disclosure. The detector 300 includes a housing 310, ascintillator 320, a bottom multi-pixel optical sensor 330, and anoptional top multi-pixel optical sensor 350.

The scintillator 320 includes a first surface 312 and a second surface314 that is spaced from the first surface 312 and parallel to the firstsurface 312. The scintillator 320 also includes edges including a bottomedge 318 and a top edge 316.

The detector 300 includes reflective surfaces 326, 328 adjacent to thefirst surface 312 and the second surface 314, respectively. For example,the reflective surfaces 326, 328 may be parallel to the first surface312 and the second surface 314. The reflective surfaces 326, 328 may bepositioned in relative alignment with each other and with thescintillator 320.

The bottom multi-pixel optical sensor 330 is positioned adjacent to thebottom edge 318. The optional top multi-pixel optical sensor 350 ispositioned adjacent to the top edge 316. For example, the bottommulti-pixel optical sensor 330 and the optional top multi-pixel opticalsensor 350 may be positioned with a light-sensitive surfaceperpendicular to the first surface 312 and the second surface 314. Insome examples, the bottom multi-pixel optical sensor 330 and theoptional top multi-pixel optical sensor 350 can be positioned with lightsensitive regions of pixels facing the scintillator 320. Similar to thedetector 100, though not shown in FIG. 3, the detector 300 operablyconnects to a power source, a processor, a display, and a data storage.

In operation, a nuclear radiation source 302 emits nuclear radiation,e.g., a neutron 304. The neutron 304 enters the housing 310 and impactsthe scintillator 320. The scintillator 320 absorbs energy from theneutron 304 and emits the energy as a photon 324.

The photon 324 can reflect one or more times off of the reflectivesurfaces 326, 328. For example, the photon 324 can reflect off of thereflective surface 328 in the direction of the bottom edge 318, passthrough the scintillator 320, and reflect off of the reflective surface326. The photon 324 can continue to reflect off of the reflectivesurfaces 326, 328 until the photon 324 exits the scintillator 320 at thebottom edge 318. In this way, the reflective surfaces 326, 328 can forma channel to conduct the photon 324 to the bottom edge 318. Similarly,the reflective surfaces 326, 328 can conduct photons to the top edge316.

The bottom multi-pixel optical sensor 330 can receive the photon 324 atone or more pixels. The multi-pixel optical sensor 330 can transmitphoton data signals 322 to the processor. The photon data signals 322can indicate spatial locations of individual pixels that detected thephoton 324. The photon data signals 322 can also include temporal dataindicating the relative timing between different photon detections.

The top multi-pixel optical sensor 350 can receive photons caused byinteractions between neutrons and the scintillator 320, and reflected bythe reflective surfaces 326, 328. The top multi-pixel optical sensor 350can transmit photon data signals 332 to the processor.

As described with reference to FIG. 1, the processor can generate, fromthe photon data signals 322, 332, spatially and temporally resolvedimages of radiation incident on the scintillator 320. The processor cancontrol operation of the display to present the image.

The processor can analyze the photon data signals 322, 332 and theimages of incident radiation to determine additional characteristics ofnuclear flux. The processor can also analyze the photon data signals322, 332 to correct for multiple nuclear radiation interactions.

Though FIG. 3 illustrates a detector 300 with the bottom multi-pixeloptical sensor 330 and the optional top multi-pixel optical sensor 350,other combinations are possible. For example, a detector can include anynumber of multi-pixel optical sensors. Each multi-pixel optical sensorcan be positioned to receive photons from any edge of the scintillator.In some examples, e.g., for a scintillator with a rectangular prismshape, the scintillator can include one or more side edges, and thedetector can include one or more multi-pixel optical sensors positionedadjacent to each of the side edges.

FIG. 4 is a diagram of an exemplary nuclear radiation detector 400 withreflective surfaces around each of a plurality of scintillatorsaccording to implementations of the present disclosure.

The detector 400 includes a housing 410, a first scintillator 420, and afirst multi-pixel optical sensor 430. The detector 400 also includes asecond scintillator 440 and a second multi-pixel optical sensor 450.Similar to the detector 100, though not shown in FIG. 4, the detector400 operably connects to a power source, a processor, a display, and adata storage.

The first scintillator 420 includes a first surface 412 and a secondsurface 414 that is spaced from the first surface 412 and parallel tothe first surface 412. The scintillator 420 also includes edgesincluding a bottom edge 418 and a top edge 416.

The detector 400 includes reflective surfaces 426, 428 adjacent to thefirst surface 412 and the second surface 414, respectively. For example,the reflective surfaces 426, 428 may be parallel to the first surface412 and the second surface 414. The reflective surfaces 426, 428 may bepositioned in relative alignment with each other and with thescintillator 420.

The bottom multi-pixel optical sensor 430 is positioned adjacent to thebottom edge 418. For example, the bottom multi-pixel optical sensor 430may be positioned with a light-sensitive surface perpendicular to thefirst surface 412 and the second surface 414. In some examples, thebottom multi-pixel optical sensor 430 can be positioned with lightsensitive regions of pixels facing the scintillator 420.

In operation, a nuclear radiation source 402 emits nuclear radiation,e.g., a neutron 404. The neutron 404 travels with a directionrepresented by arrow 406. The neutron 404 enters the housing 410 andimpacts the scintillator 420. The scintillator 420 absorbs energy fromthe neutron 404 and emits the energy as a photon 424. As a result ofinteracting with the scintillator 420, the neutron 404 may slow anddeflect. The neutron 404 can continue to travel through the scintillator420 and the housing 410 at a direction represented by arrow 415.

The photon 424 can reflect one or more times off of the reflectivesurfaces 426, 428. For example, the photon 424 can reflect off of thereflective surface 428, pass through the scintillator 420, and reflectoff of the reflective surface 426. The photon 424 can continue toreflect off of the reflective surfaces 426, 428 until the photon 424exits the scintillator 420 at the bottom edge 418. In this way, thereflective surfaces 426, 428 can form a channel to conduct the photon424 to the bottom edge 418.

The bottom multi-pixel optical sensor 430 can receive the photon 424 atone or more pixels. The multi-pixel optical sensor 430 can transmitphoton data signals 422 to the processor. The photon data signals 422can indicate spatial locations of individual pixels that detected thephoton 424. The photon data signals 422 can also include temporal dataindicating the relative timing between different photon detections.

The neutron 404 travels in the direction represented by the arrow 415.The neutron 404 impacts the scintillator 440. The scintillator 440absorbs energy from the neutron 404 and emits the energy as a photon434. Similar to the photon 424, the photon 434 can reflect off ofreflective surfaces adjacent to surfaces of the scintillator 440 untilthe second multi-pixel optical sensor 450 receives the photon 434.

The second multi-pixel optical sensor 450 receives the photon 434 at oneor more pixels. The second multi-pixel optical sensor 450 can transmitphoton data signals 432 to the processor. The photon data signals 432can indicate spatial locations of individual pixels that detected thephoton 424. The photon data signals 432 can also include temporal dataindicating the relative timing between different photon detections.

As described with reference to FIG. 2, the processor can generate, fromthe photon data signals 422, 432, spatially and temporally resolvedimages of radiation incident on the scintillators 420, 440. Theprocessor can control operation of the display to present the image. Theprocessor can analyze the photon data signals 422, 432 and the images ofincident radiation to determine additional characteristics of nuclearflux. The processor can also analyze the photon data signals 422, 432 tocorrect for multiple nuclear radiation interactions.

Though FIG. 4 illustrates the detector 400 with two neutronscintillators 420, 440, other scintillator combinations are possible.For example, a detector can include any number or combination of neutronscintillators, gamma scintillators, and neutron/gamma scintillators. Thearrangement of neutron scintillators, gamma scintillators, andneutron/gamma scintillators can be in any order with respect to thedirection of incident nuclear radiation. Each multi-pixel optical sensorcan be positioned to receive photons from any combination of one or morescintillators.

FIG. 5 is a diagram of an exemplary nuclear radiation detector 500 witha large-area scintillator according to implementations of the presentdisclosure.

The detector 500 includes a housing 510, a large-area scintillator 520,and a multi-pixel optical sensor 530. The detector 500 also includes alens 525. The large-area scintillator 520 can be a scintillator with anarea of, e.g., 100 square centimeters, 300 square centimeters, or 600square centimeters.

The housing 510 encloses the large-area scintillator 520, the lens 525,and the multi-pixel optical sensor 530. The housing 510 can isolate thelarge-area scintillator 520, the lens 525, and the multi-pixel opticalsensor 530 from external light. For example, the housing can isolate thescintillator 120 and optical sensor 130 from external light to preventfalse radiation detection signals. Similar to the detector 100, thoughnot shown in FIG. 5, the detector 500 operably connects to a powersource, a processor, a display, and a data storage.

The lens 525 is positioned, relative to the large-area scintillator 520,to receive photons emitted by the large-area scintillator 520. Forexample, the lens 525 can be positioned in relative alignment with thescintillator 520. In some examples, the lens 525 can be positioned suchthat the scintillator 520 is between the lens 525 and a radiationsource. In some examples, the lens 525 is positioned within a minimumand maximum distance to the scintillator 520, e.g., between tencentimeters and one hundred centimeters from the scintillator 520.

The lens 525 is positioned to focus the photons emitted by thelarge-area scintillator 520 onto the multi-pixel optical sensor 530. Forexample, the lens 525 can be positioned in relative alignment with, andbetween, the scintillator 520 and the multi-pixel optical sensor 530.

In some examples, the multi-pixel optical sensor 530 can be positionedwith light sensitive regions of pixels facing the lens 525. In someexamples, the multi-pixel optical sensor 530 is positioned within aminimum and maximum distance to the lens 525, e.g., between one-tenth ofa centimeter and ten centimeters from the lens 525. In some examples,the multi-pixel optical sensor 530 is positioned at or near a focalpoint of the lens 525.

In operation, a nuclear radiation source 502 emits nuclear radiation,e.g., neutrons 504, 506. The neutrons 504, 506 each enter the housing510 and impact the large-area scintillator 520. The large-areascintillator 520 absorbs energy from the neutrons 504, 506 and emits theenergy as photons 524, 534 respectively.

Due to the large area of the large-area scintillator 520, the large-areascintillator 520 emits photons 524, 534 over a wide area. The lens 525focuses the photons 524, 534 onto the multi-pixel optical sensor 530.The lens 525 can focus the photons 524, 534 onto the multi-pixel opticalsensor 530 by refracting each of the photons 524, 534 inward toward themulti-pixel optical sensor 530. Thus, though the multi-pixel opticalsensor 530 may have a small area, the multi-pixel optical sensor 530 canreceive photons caused by interactions with nuclear radiation over alarge area.

The multi-pixel optical sensor 530 receives the photons 524, 534 at oneor more pixels. The multi-pixel optical sensor 530 can transmit photondata signals 522 to the processor. The photon data signals 522 canindicate spatial locations of individual pixels that detected thephotons 524, 534. The photon data signals 522 can also indicate temporaldata indicating the relative timing between different photon detections.

The processor can generate, from the photon data signals 522, 532, aspatially and temporally resolved image of radiation incident on thelarge-area scintillator 520. The processor can control operation of thedisplay to present the image.

FIG. 6 depicts a schematic diagram of a computer system that may beapplied to any of the computer-implemented methods and other techniquesdescribed herein.

For example, the system, or portions thereof, can be implemented as theGMD controller or the server system described above in reference toFIGS. 1 and 2A. The system 600 can be used to carry out the operationsdescribed in association with any of the computer-implemented methodsdescribed previously, according to some implementations. In someimplementations, computing systems and devices and the functionaloperations described in this specification can be implemented in digitalelectronic circuitry, in tangibly-embodied computer software orfirmware, in computer hardware, including the structures disclosed inthis specification (e.g., system 600) and their structural equivalents,or in combinations of one or more of them. The system 600 is intended toinclude various forms of digital computers, such as laptops, desktops,workstations, personal digital assistants, servers, blade servers,mainframes, and other appropriate computers, including vehiclesinstalled on base units or pod units of modular vehicles. The system 600can also include mobile devices, such as personal digital assistants,cellular telephones, smartphones, and other similar computing devices.Additionally, the system can include portable storage media, such as,Universal Serial Bus (USB) flash drives. For example, the USB flashdrives may store operating systems and other applications. The USB flashdrives can include input/output components, such as a wirelesstransducer or USB connector that may be inserted into a USB port ofanother computing device.

The system 600 includes a processor 610, a memory 620, a storage device630, and an input/output device 640. Each of the components 610, 620,630, and 640 are interconnected using a system bus 650. The processor610 is capable of processing instructions for execution within thesystem 600. The processor may be designed using any of a number ofarchitectures. For example, the processor 610 may be a CISC (ComplexInstruction Set Computers) processor, a RISC (Reduced Instruction SetComputer) processor, or a MISC (Minimal Instruction Set Computer)processor.

In one implementation, the processor 610 is a single-threaded processor.In another implementation, the processor 610 is a multi-threadedprocessor. The processor 610 is capable of processing instructionsstored in the memory 620 or on the storage device 630 to displaygraphical information for a user interface on the input/output device640.

The memory 620 stores information within the system 600. In oneimplementation, the memory 620 is a computer-readable medium. In oneimplementation, the memory 620 is a volatile memory unit. In anotherimplementation, the memory 620 is a non-volatile memory unit.

The storage device 630 is capable of providing mass storage for thesystem 600. In one implementation, the storage device 630 is acomputer-readable medium. In various different implementations, thestorage device 630 may be a floppy disk device, a hard disk device, anoptical disk device, or a tape device.

The input/output device 640 provides input/output operations for thesystem 600. In one implementation, the input/output device 640 includesa keyboard and/or pointing device. In another implementation, theinput/output device 640 includes a display unit for displaying graphicaluser interfaces.

The features described can be implemented in digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. The apparatus can be implemented in a computerprogram product tangibly embodied in an information carrier, e.g., in amachine-readable storage device for execution by a programmableprocessor; and method steps can be performed by a programmable processorexecuting a program of instructions to perform functions of thedescribed implementations by operating on input data and generatingoutput. The described features can be implemented advantageously in oneor more computer programs that are executable on a programmable systemincluding at least one programmable processor coupled to receive dataand instructions from, and to transmit data and instructions to, a datastorage system, at least one input device, and at least one outputdevice. A computer program is a set of instructions that can be used,directly or indirectly, in a computer to perform a certain activity orbring about a certain result. A computer program can be written in anyform of programming language, including compiled or interpretedlanguages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment.

Suitable processors for the execution of a program of instructionsinclude, by way of example, both general and special purposemicroprocessors, and the sole processor or one of multiple processors ofany kind of computer. Generally, a processor will receive instructionsand data from a read-only memory or a random access memory or both. Theessential elements of a computer are a processor for executinginstructions and one or more memories for storing instructions and data.Generally, a computer will also include, or be operatively coupled tocommunicate with, one or more mass storage devices for storing datafiles; such devices include magnetic disks, such as internal hard disksand removable disks; magneto-optical disks; and optical disks. Storagedevices suitable for tangibly embodying computer program instructionsand data include all forms of non-volatile memory, including by way ofexample semiconductor memory devices, such as EPROM, EEPROM, and flashmemory devices; magnetic disks such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,ASICs (application-specific integrated circuits).

To provide for interaction with a user, the features can be implementedon a computer having a display device such as a CRT (cathode ray tube)or LCD (liquid crystal display) monitor for displaying information tothe user and a keyboard and a pointing device such as a mouse or atrackball by which the user can provide input to the computer.Additionally, such activities can be implemented via touchscreenflat-panel displays and other appropriate mechanisms.

The features can be implemented in a computer system that includes aback-end component, such as a data server, or that includes a middlewarecomponent, such as an application server or an Internet server, or thatincludes a front-end component, such as a client computer having agraphical user interface or an Internet browser, or any combination ofthem. The components of the system can be connected by any form ormedium of digital data communication such as a communication network.Examples of communication networks include a local area network (“LAN”),a wide area network (“WAN”), peer-to-peer networks (having ad-hoc orstatic members), grid computing infrastructures, and the Internet.

The computer system can include clients and servers. A client and serverare generally remote from each other and typically interact through anetwork, such as the described one. The relationship of client andserver arises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular implementations of particularinventions. Certain features that are described in this specification inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular implementations of the subject matter have beendescribed. Other implementations are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results. Inaddition, the processes depicted in the accompanying figures do notnecessarily require the particular order shown, or sequential order, toachieve desirable results. In certain implementations, multitasking andparallel processing may be advantageous.

As used herein, the terms “perpendicular,” “orthogonal,” “substantiallyperpendicular,” or “substantially orthogonal” refer to a relationbetween two elements (e.g., lines, axes, planes, surfaces, orcomponents) that forms a ninety degree (perpendicular) angle withinacceptable engineering, machining, or measurement tolerances. Forexample, two surfaces can be considered orthogonal to each other if theangle between the surfaces is within an acceptable tolerance of ninetydegrees (e.g., ±1-2 degrees).

As used herein, the terms “aligned,” “substantially aligned,”“relatively aligned” “parallel,” or “substantially parallel” refer to arelation between two elements (e.g., lines, axes, planes, surfaces, orcomponents) as being oriented generally along the same direction withinacceptable engineering, machining, drawing measurement, or part sizetolerances such that the elements do not intersect or intersect at aminimal angle. For example, two surfaces can be considered aligned witheach other if surfaces extend along the same general direction of adevice.

What is claimed is:
 1. A nuclear radiation detector comprising: ahousing comprising therein: a scintillator; and a multi-pixel opticalsensor positioned, relative to the scintillator, to receive photonsemitted by the scintillator in response to interactions with nuclearradiation, wherein the housing isolates the scintillator and themulti-pixel optical sensor from external light; one or more processorsoperably connectable to the multi-pixel optical sensor; and one or moredata stores coupled to the one or more processors having instructionsstored thereon which, when executed by the one or more processors,causes the one or more processors to perform operations comprising:responsive to the multi-pixel optical sensor detecting photons emittedby the scintillator, receiving, from the multi-pixel optical sensor,data signals indicating 1) spatial locations of individual pixels thatdetected the photons and 2) temporal data indicating when the detectionsoccurred; and generating, from the data signals, a spatially andtemporally resolved image of radiation incident on the scintillator. 2.The detector of claim 1, wherein the multi-pixel optical sensor is adynamic vision sensor.
 3. The detector of claim 1, wherein a timeresolution of the image is less than one millisecond.
 4. The detector ofclaim 1, wherein the scintillator is positioned between a firstreflector and a second reflector, each of the first reflector and thesecond reflector comprising a reflective surface that faces oppositeside surfaces of the scintillator, and wherein the multi-pixel opticalsensor is positioned adjacent an edge of the scintillator that is notbounded by either the first reflector or the second reflector.
 5. Thedetector of claim 1, wherein the scintillator is a large-areascintillator, the detector further comprising a lens positioned to focusphotons emitted by the scintillator in response to interactions withnuclear radiation onto the multi-pixel optical sensor.
 6. The detectorof claim 5, wherein: the lens is positioned between the large-areascintillator and the multi-pixel optical sensor, and the large-areascintillator, the lens, and the multi-pixel optical sensor aresubstantially aligned.
 7. The detector of claim 1, the operationsfurther comprising: determining, from the spatially and temporallyresolved image of radiation incident on the scintillator, one or morenuclear radiation flux characteristics.
 8. The detector of claim 7,wherein the one or more nuclear radiation flux characteristics compriseat least one of a velocity, a direction of travel, a wavelength, and anenergy of the radiation incident on the scintillator.
 9. The detector ofclaim 1, wherein the multi-pixel optical sensor is positioned withlight-sensitive regions of the pixels facing the scintillator.
 10. Thedetector of claim 1, the housing further comprising therein: a secondscintillator spaced from the scintillator; and a second multi-pixeloptical sensor positioned, relative to the second scintillator, toreceive photons emitted by the second scintillator in response tointeractions with nuclear radiation, wherein the housing isolates thesecond scintillator and the second multi-pixel optical sensor fromexternal light; the operations further comprising: responsive to thesecond multi-pixel optical sensor detecting photons emitted by thesecond scintillator, receiving, from the second multi-pixel opticalsensor, data signals indicating 1) spatial locations of individualpixels that detected the photons and 2) temporal data indicating whenthe detections occurred; generating, from the data signals, a secondspatially and temporally resolved image of radiation incident on thesecond scintillator; and determining, from the spatially and temporallyresolved image of radiation incident on the scintillator, and the secondspatially and temporally resolved image of radiation incident on thesecond scintillator, a nuclear radiation velocity and direction betweenthe scintillator and the second scintillator.
 11. The detector of claim10, wherein one or more of the scintillator and the second scintillatoremits photons in response to interactions with neutrons.
 12. Thedetector of claim 10, wherein one or more of the scintillator and thesecond scintillator emits photons in response to interactions with gammarays.
 13. The detector of claim 10, wherein the scintillator, themulti-pixel optical sensor, the second scintillator, and the secondmulti-pixel optical sensor are substantially aligned.
 14. A nuclearradiation detection system comprising: a housing comprising therein: ascintillator; and a multi-pixel optical sensor positioned, relative tothe scintillator, to receive photons emitted by the scintillator inresponse to interactions with nuclear radiation, wherein the housingisolates the scintillator and the multi-pixel optical sensor fromexternal light; one or more processors operably connectable to themulti-pixel optical sensor; a display operably coupled to the one ormore processors; and one or more data stores coupled to the one or moreprocessors having instructions stored thereon which, when executed bythe one or more processors, causes the one or more processors to performoperations comprising: responsive to the multi-pixel optical sensordetecting photons emitted by the scintillator, receiving, from themulti-pixel optical sensor, data signals indicating 1) spatial locationsof individual pixels that detected the photons and 2) temporal dataindicating when the detections occurred; generating, from the datasignals, a spatially and temporally resolved image of radiation incidenton the scintillator; and providing, for presentation on the display, thespatially and temporally resolved image of the radiation incident on thescintillator.
 15. The system of claim 14, wherein the multi-pixeloptical sensor is a dynamic vision sensor.
 16. The system of claim 14,wherein a time resolution of the image is less than one millisecond. 17.The system of claim 14, wherein the scintillator is positioned between afirst reflector and a second reflector, each of the first reflector andthe second reflector comprising a reflective surface that faces oppositeside surfaces of the scintillator, and wherein the multi-pixel opticalsensor is positioned adjacent an edge of the scintillator that is notbounded by either the first reflector or the second reflector.
 18. Thesystem of claim 14, wherein the scintillator is a large-areascintillator, the detector further comprising a lens positioned to focusphotons emitted by the scintillator in response to interactions withnuclear radiation onto the multi-pixel optical sensor.
 19. The system ofclaim 18, wherein: the lens is positioned between the large-areascintillator and the multi-pixel optical sensor, and the large-areascintillator, the lens, and the multi-pixel optical sensor aresubstantially aligned.
 20. A method for nuclear radiation detectioncomprising: receiving, from a multi-pixel optical sensor that ispositioned, relative to a scintillator, to receive photons emitted bythe scintillator in response to interactions with nuclear radiation,data signals indicating 1) spatial locations of individual pixels thatdetected the photons and 2) temporal data indicating when the detectionsoccurred; generating, from the data signals, a spatially and temporallyresolved image of radiation incident on the scintillator; and providing,for presentation on a display, the spatially and temporally resolvedimage of the radiation incident on the scintillator.